Boosting capacitive performance of manganese oxide nanorods by decorating with three-dimensional crushed graphene

This work reports the rational design of MnO_x nanorods on 3D crushed reduced graphene oxide (MnO_x/C-rGO) by chemical reduction of Ni-incorporated graphene oxide (GO) followed by chemical etching to remove Ni. The resulting MnO_x/C-rGO composite synergistically integrates the electronic properties and geometry structure of MnO_x and 3D C-rGO. As a result, MnO_x/C-rGO shows a significantly higher specific capacitance (C_sp) of 863 F g^-1 than MnO_x/2D graphene sheets (MnO_x/S-rGO) (373 F g^-1) and MnO_x (200 F g^-1) at a current density of 0.2 A g^-1. Furthermore, when assembled into symmetric supercapacitors, the MnO_x/C-rGO-based device delivers a higher C_sp (288 F g^-1) than MnO_x/S-rGO-based device (75 F g^-1) at a current density of 0.3 A g^-1. The superior capacitive performance of the MnO_x/C-rGO-based symmetric device is attributed to the enlarged accessible surface, reduced lamellar stacking of graphene, and improved ionic transport provided by the 3D architecture of MnO_x/C-rGO. In addition, the MnO_x/C-rGO-based device exhibits an energy density of 23 Wh kg^-1 at a power density of 113 Wkg^-1, and long-term cycling stability, demonstrating its promising potential for practical application.